Compact Discs (CDs) are delivered in the beginning as music CDs which are a so called CD-DA (Compact Disc-Digital Audio), and the standard thereof has been extended to CDs for multimedia. As the representative standard of CD, there are standardized
CD-DA format, PA1 CD-ROM (Compact Disc-Read Only Memory) format, PA1 CD-I (Compact Disc-Interactive) format, and PA1 CD-ROM/XA (CD-ROM Extended Architecture) format.
The CD-DA format is the format for audio data. This CD-format is the format which provides the basis for other formats, and prescribes (specifies) the physical structure and the signal processing system of the disc.
The CD-ROM format is the format extended for computer data. In this CD-ROM format, as the physical block structure, two modes of the mode 1 where Error Detection Code (hereinafter abbreviated as EDC) and Error Correction Code (hereinafter abbreviated as ECC) are added and the mode 2 where EDC/ECC is omitted are standardized.
The CD-I format is the format extended so as to include picture data or character data, etc. in addition to audio data. The block structure in this CD-I format is the block structure of the mode 2 in the CD-ROM format. In this CD-I format, as the physical block structure, two modes of the form 1 in which EDC/ECC is added and the form 2 in which EDC/ECC is omitted are standardized.
The CD-ROM/XA format prescribes that, for the purpose of allowing computer data and audio data to be synchronous with each other, the computer data and the audio data are caused to be interleaved. The block structure in this CD-ROM/XA format is the block structure of the mode 2 in the CD-ROM format. In this CD-ROM/XA format, as the physical block structure, two modes of the form 1 in which EDC/ECC is added and the form 2 in which EDC/ECC is omitted are standardized.
Meanwhile, in recent years, there have been proposed CD-R (Compact Disc-Recordable) discs in which a recording surface on which organic (system) recording material is coated is provided on one surface of the disc of which size is the same as that of the compact disc so that arbitrary data can be written onto the recording surface by light beams. In the CD-R discs, the CD-MO (Compact Disc-Magneto Optical) format for rewritable CD and the CD-WO (Compact Disc-Write Once) format for write once type-CD are standardized. In addition, CDs of various formats as described above have been prepared by making use of the CD-R discs.
In the case of the format of CD, one track is of one collective file structure in which data has been written only once, or segments of audio data.
In the beginning, the CD-DA discs and/or the CD-ROM discs, etc. were reproduction (playback) only discs, and were single session (area) discs provided with single session constituted with one track or more consisting of audio track where audio data is recorded and/or data track where computer data is recorded. However, the (data) once writable CD-R discs are adapted so that plural sessions can be provided on the disc. Thus, multi-session discs utilizing such CD-R disc have been provided.
Meanwhile, audio data which can be recorded on the CD-R disc by the CD-DA format is 16 bit data. Accordingly, it is impossible to record audio data of the master tape recorded by the number of bits more than 16 bit, for example, as it is.
In view of the above, the so-called noise shaping or dither is utilized by the super bit mapping in which auditory sense is taken into consideration, or the like to record audio data more than 16 bits onto the CD-R disc by the CD-DA format, in the state where those audio data are caused to be set of 16 bit data, without injuring the sound quality.
By these technologies, CD-R discs recorded by the CD-DA format have been able to be reproduced by the ordinary CD player. However, since the data quantity is essentially decreased, it was impossible to reproduce the same sound as sound of the master tape.
Moreover, if the CD-ROM format is used, it becomes possible to record audio data of the number of bits more than 16 bits as described above onto the CD-R disc. However, since compatibility with CDs of the CD-DA format is lost, such CD-R discs cannot be reproduced by the ordinary CD player.
Further, there is restriction in the conventional format of the CD-R disc. Namely, e.g., if CD-R disc prepared in such a manner that areas respectively called audio session recorded by the CD-DA format and data session recorded by the CD-ROM format are mixed on the same disc by the so-called multi-session format is reproduced by the ordinary CD player, since codes which might not be recognized are recorded, there is the possibility that reproduction of audio data of the audio track recorded in the audio session may become impossible, and/or data of the data track recorded in the data session may be erroneously reproduced as audio data.
This invention has been made in view of actual circumstances as described above, and its object is to provide a recording medium which can maintain compatibility with the conventional CD player, and can be reproduced in the state of high sound quality at the reproducing apparatus of higher rank, a recording apparatus capable of recording audio data onto such a recording medium in the state where high sound quality is maintained, and a reproducing method and a reproducing apparatus for reproducing such recording medium in the state of high sound quality.